Electrical connections for splicing together pluralities of insulated conductors for telecommunications have been made in a number of ways with connectors that are available in the marketplace. One of these is by way of terminals which include a post and nut arrangement. In those, an end of an insulated conductor is bared and wrapped about a threaded post with a nut being turned along the post to engage the conductor end and to hold it in engagement with a terminal block from which the post extends. Typically, an opposite end of the post is formed to have another conductor wrapped thereabout. While this arrangement results in a reliable connection, it is labor intensive and escalates costs.
Connectors are also available which do not require the stripping of the insulation from an end of the conductor prior to making the connection. A connector which is widely used in telecommunications for interconnecting insulated conductors in which the conductive elements are solid is one which includes split beam contact elements. The contact element, in one well-known product, includes a center portion with beams extending colinearly therefrom. Each of the beams is bifurcated with the furcations of each forming a conductor-receiving slot. A plurality of the split beam contact elements are mounted in a dielectric housing which may be called a terminal block. To establish a connection, an insulated conductor is moved into one slot and another conductor into the opposite slot. Surfaces that define the entrances to the slots and the slots themselves are configured to engage the conductive element of each conductor to establish an electrical connection between the conductors. See for example U.S. Pat. No. 3,496,522 which issued on Feb. 17, 1970 in the names of B. C. Ellis et al and U.S. Pat. Nos. 3,611,264 and 3,772,635.
A connector system which includes the split beam contact element is disclosed and claimed in U.S. Pat. No. 3,858,158 which issued on Dec. 31, 1974 in the names of R. W. Henn et al. and lowers significantly the cost of making connections. The above-identified connector system includes an elongated index strip for holding a plurality of insulated conductors of a first cable in a spaced array and a connector module which includes a plurality of split beam type metallic contact elements. When the connector module is assembled to the index strip, end portions of the contact elements become electrically connected to the conductors held in the index strip. Afterwards, conductors from a second cable are assembled to the connector module so that the opposite end portions of the contact elements are electrically connected to them and hence to the conductors of the first cable. In E. W. Becker et al U.S. Pat. No. 4,148,138 which issued Apr. 10, 1979, a tool is shown for assembling corresponding pluralities of insulated conductors of cable ends to this type connector to electrically interconnect the conductors.
One problem with the split beam contact elements relates to the capability of using one slot to terminate two or more conductors or conductors of different guages. When the insulated conductor first placed in the slot is moved farther inwardly, it tends to spread apart the side walls of the furcations which define the slot and which in prior art connectors are generally resilient. Disadvantageously, the surfaces which define the slot can be deflected to an extent that precludes the establishment and maintenance of a satisfactory gastight connection with the conductive element of a second conductor that is moved into the slot. The resilience of the furcations also presents a problem when attempting to connect conductors of a range of gauge sizes. A solution to this problem is to maintain an inventory of different connectors for use with different gauge size cables, but this would increase costs.
For the same reason, the conventional split beam connector does not provide an altogether effective connective mechanism for stranded conductors. When a stranded conductor is moved into the slot, the furcations which are resilient are deflected. The configuration of the conductor is deformed and the individual strand elements become rearranged in the slot with some diminution of the nicking of the elements.
Another concern which is a continuing one in the connector art relates to compactness. Because of the number of conductor pairs in presently used cables, a relatively large number of the connector systems such as those disclosed in the above-identified Henn et al patent are required to complete a splice. Each of these systems, which is designed to splice twenty-five pairs of insulated conductors, has a length of about eight inches, a width of about a quarter of an inch and a height of about one and one half inches. Multiply these dimensions by the number of twenty-five pair splices in one of the large pair size cables and it becomes readily apparent that a closure therefor must be substantial in size. The connector system should be as small as possible not only for reasons of material costs, but also to reduce the space required in manholes, vaults, and closures.
Economy of space has been achieved to some extent by the system disclosed in the Henn et al patent and by a connector such as one shown in U.S. Pat. No. 3,708,779. Therein the connections are made also by split beam contact elements but they are arranged in rows and are staggered as between rows to reduce their center-to-center spacing.
Most, if not all the splicing type connectors which are available commercially include provisions for severing end portions of the conductors which extend beyond the connection element such as, for example, the split beam contact element. In the Henn et al connector, an anvil surface is provided for supporting the end portions of the conductors to facilitate their severance by the blade of a tool such as that disclosed in the Becker et al patent. In the connector shown in U.S. Pat. No. 3,708,779, cut-off blades are mounted in one of the plastic elements of the system. When the elements are assembled together, the blades sever the end portions of the conductors which extend beyond the split beam connections.
Another problem relates to the accuracy of and the testing for connections. Typically, a test is made which determines only the correctness of a pair sequence along the connector. Although the conductor pairs may be connected along the connector in the correct sequence, the conductors of one or more pairs, which are color coded, may be reversed. As a result, the conductor of one pair in one slot of a split beam contact element may not be the correct one for connection to a conductor of another pair in the other slot of the contact element. This incorrect association of spliced conductors may be overcome by visual inspection. However, with the prior art connector systems, the conductors which are spliced together are generally supported in stacked plastic connector elements. Because of this arrangement, the conductors to be spliced together are spaced apart which makes paired identification before connection somewhat difficult.
What is needed is a multi-conductor connection system which is capable of establishing and maintaining suitable electrical connections with stranded or solid-wire-like conductors. Further, it should be able to establish and maintain electrical engagement with one or more conductors of the same or different gauge size. With today's seemingly endless growth of telecommunications, there is still a need for an electrical connector that is relatively small and that fills the above needs and which retains the advantages of the split beam contact element such as its bilateral connectorability. It would also be most desirable to provide a system which facilitates improved visual inspection or verification either in the factory or in the field.
Lengths of communications cables are connected together in the field at splice locations, such as in manholes or overhead adjacent to poles. That such an operation is expensive should be apparent when considering the environment in which the splice is made. In order to reduce the effort required in such environments, there has been a trend toward factory connectorization of cables. Preconnectorized cable ends are simply assembled together in the field with simultaneous connections being made between all the conductors assembled to one connector element and then connected to another element. A connector system which meets the needs described hereinbefore should also be one which preserves the capability of being used in the factory to connectorize cable ends prior to shipment.